Merge trunk. 
Convert Tcl_SetVar/Tcl_UnsetVar/Tcl_GetVar/Tcl_TraceVar to macros, calling the *2 variants of the function. No change of functionality.
Merge trunk. 
Convert Tcl_UntraceVar to macro, calling Tcl_UntraceVar2 in stead. No change of functionality.
merge-mark
fix doc: return value of Tcl_FindExecutable